1. Field of the Invention
This invention relates to a steering system for a vehicle, and more particularly to a steering system which can reliably damp out shocks applied when a vehicle runs into something or collides with another vehicle.
2. Description of the Related Art
A variety of steering systems have been known and are currently available. One example of a steering system comprises a steering shaft which is coupled to a steering wheel at one end, passes through a dashboard, and is connected to a steering gear box at the other end.
Such a steering system has been proposed in Japanese Patent Laid-Open Publication No. Hei 4-108,482. With this steering system, an intermediate shaft passes through a dashboard. A set plate is attached, via a bearing, to the dashboard at a position where the intermediate shaft passes through. This set plate is designed to be relatively less rigid so that it may be easily pushed toward a front part of the vehicle. Thus, a lower end of a steering column can be displaced without being disturbed by the dashboard when shocks are applied to the steering system. In other words, the set plate promotes displacement of the steering system toward the front part of the vehicle.
Such a set plate is designed to be easily deformed, but cannot completely free the intermediate shaft from the dashboard. Sometimes, the set plate may be deformed in such a manner that it may interfere with the intermediate shaft or the steering column, thereby obstructing the steering column from being displaced toward the front part of the vehicle. This means that shocks cannot be damped at a position where the steering column is made immovable.
Further, shocks caused by the deformed set plate may change a positional relationship between the steering column and the bearing, which would cause the bearing to interfere with the steering column. Thus, shocks cannot be damped at such a position.
To overcome the foregoing obstructions, the steering column of the conventional steering system is required to include a damper mechanism having high damping efficiency, which means that the vehicle would become more expensive.
Further, there is a possibility that a steering shaft angle may vary due to the foregoing obstructions. Therefore, if the vehicle is provided with an air bag system, a larger air bag has to be used to protect a driver, taking a variation of the steering shaft angle into consideration.